Rotary grinding implement



1953 F. c. FEHRMAN ROTARY GRINDING IMPLEMENT Filed Nov. 24, 1952 INVENTOR FREDERICK C. Fame MAN ATTORNEY Patented Oct. 20, 1953 UNITED STATES 2,655,725 ROTARY GRINDING IMPLEMENT Frederick C. Fehrman, Washington, D.

Application November 24, 1952, Serial No. 322,194

4 Claims.

by extreme compactness and slenderness, so that it may be readily introduced into the chinchillas mouth which is extremely small.

A further important object is to provide a rotary grinding implement of the above-mentioned character having a readily adjustable guard for the small rotary burr, for the purpose of preventing injury to the mouth of the animal while it tusks are being ground.

A further object is to provide-an implement of the above-mentioned type, wherein the adjustable guard for the burr serves as a bearing for the spindle of the burr.

Still another object of the invention is to provide in a grinding implement of the abovementioned character a rotary guard for the grinding burr which is adjustable about the entire circumference of the burr with the finger, while the implement is being held in the hand.

Other objects and advantages of the invention will be apparent during the course of the following description.

In the accompanying drawings, forming a part of this application, and in which like numerals are employed to designate like parts throughout the same, 7

Figure 1 is a side elevation on a greatly enlarged scale of a rotary grinding implement embodying the invention, part broken away,

Figure 2 is a further side elevation of the implement taken at right angles to Figure 1,

Figure 3 is a further enlarged central vertical longitudinal section through the implement,

Figure 4 is a plan view on an enlarged scale of an adjustable guard and associated elements removed,

Figure 5 is a side elevation of the guard and associated elements, shown in Figure 4.

Figure 6 is a further side elevation of the guard taken at right angles to Figure 5,

Figure 7 is an enlarged fragmentary vertical section on line 1-1 of Figure 5,

Figure 8 is an enlarged fragmentary side elevation of a chuck and flexible drive shaft removed,

Figure 9 is an end elevation 'of the chuck, and,

Figure 10 is a side elevation of the guard and associated elements, and showing substantially the actual size of the implement,

In the drawings, where for the purpose of illustration is shown a preferred embodiment of the invention, the numeral I0 designates a flexible sheathing or tube of any suitable length, and

formed from a continuous spirally wound wire coil or the like. One end of the flexible sheathing l0 engages in an end of a cylindrical thin walled rigid sleeve ll, of brass or the like, and the end of the sleeve receiving the sheathing l0 may be crimped inwardly as at I2 for firmly securing the sheathing [0 within the sleeve ll.

As shown in Figure 3, the sheathing l0 terminates near the longitudinal center of the sleeve 1 l l. The sleeve H is preferably covered. throughout its entire length with a section of rubber tubing l3 or the like to facilitate handling the implement, and the rubber tubing section has a snug fit upon the rigid sleeve H and will not turn thereon. The sleeve II and tubing l3 constitute a handpiece.

Rotatably mounted within the end of the sleeve H remote from the sheathing I0 is an intermediate cylindrical sleeve or adapter [3, having 'a thin walled skirt portion I4 extending for a substantial distance into the sleeve II for form- 'ing an adequate bearing contact area. The end of the skirt portion I4 terminates near the adj acent end of the sheathing ID, as shown in Figure 3. The intermediate adapter l3 extends beyond the sleeve II and has an outer screw threaded end l5. The adapter I3 is provided inwardly of its screw threaded end I5 with an enlarged hexagonal turning lug I6, integral therewith, and the lug i6 is arranged adjacent to the near end of the rigid sleeve l l. The adapter l3 has a cylindrical bore ll of lesser diameter than the bore 'of the skirt portion I4, and the bore l1 leads into an enlarged counter bore or recess l8, formed in the forward screw threaded end of the adapter 13'. shoulder i9 is preferably formed between the A conically beveled bore l1 and counter bore l8, as shown.

A rotary chuck 20 has a reduced cylindrical tubular shank 2! journalled within the bore l1,

and the chuck has a forward enlarged portion or head 2| arranged within the counter bore l8 and projecting axially forwardly of the adapter [3, Figure 3. The forward end of the enlarged chuck head 2| is conically tapered at 22, and the chuck head is provided in its forward end with. a plurality of circumferentially equidistantly spaced slots 23 extending to points near the longitudinal center of the reduced shank 2|, Figure 3. The slots 23 form a plurality of resilient segmental gripping jaws 24, and the chuck 20 has a small cylindrical bore 25 extending throughout its entire length. The enlarged head 2| in the counterbore [8 preferably has its inner end 26 conically tapered for engagement with the conically tapered shoulder IS). The engagement of the shoulder IS with the tapered end 26 of the chuck head prevents the chuck from moving axially inwardly in the adapter I3.

A flexible drive shaft or cable 2! has one end firmly secured within the tubular shank 2! of the chuck, and the drive shaft 2? extends through the sleeve I l and sheathing It for connection with the power takeoff of a suitable dental engine, or the like, not shown. The drive shaft 21, as well as the flexible sheathing I!) are of any desired length to suit the convenience of the operator.

A small cylindrical grinding stone or burr 29 has a narrow elongated cylindrical spindl 33 rigidly secured thereto and having its rear end portion engageable within the chuck bore 25, as shown. When the implement is assembled, the rear end of the spindle 39 terminates near the longitudinal center of the chuck bore 25, Figure 3. A tubular clamping nut 32 has screw threaded engagement upon the screw threaded end id of adapter l3, and the boreof the nut 32 receives the chuck head 2|, as shown. The nut 32 has a reduced opening 33 in its forward end for the passage of the spindle 30, and receiving the forward extremities of the chuck jaws 23. A conically beveled shoulder 34 is formed in the nut 32 inwardly of the reduced opening 33, and when the nut 32 is tightened this shoulder 33 engages the tapered end 22 of the chuck head to force the resilient jaws 24 inwardly for tight clamping engagement with the spindle 30.

I provide an adjustable guard or shield 35 for the rotary burr 29, and this guard comprises a small cylindrical body portion or head 33 surrounding the burr 29 and having its forward end open. A relatively large side opening 38 in the body portion 35 exposes one side of the burr 29, and the side opening 38 extends throughout substantially the entire axial length of the body portion or head 35, as shown. The edges 39 of the head 36 which define the opening 38 are rounded, as shown, so that a forward corner 4| of the burr 29 is fully exposed. The formation of the side opening 38 in the cylindrical head 36 forms upon the head a substantially flat face 4! which is substantially flush with the exposed side of the cylindrical burr 29, Figure 7.

The adjustable guard 35 further comprises a narrow cylindrical sleeve 42, integrally secured to the head 35 and rotatably receiving the spindle 39, and serving as a bearing for this spindle. The sleeve 42 is provided at its rear end with an enlargement or head 42 which bears against the forward end of the clamping nut 32. The bore of the sleeve 42 is just large enough to accommodate the rotary spindle 30, and substantially smaller in diameter than the burr 29. Accordingly, when the spindle 39 is clamped within the chuck 25, the rotary guard 35 cannot shift axially forwardly for any appreciable distance, since the burr 29 cannot enter the small bore of the sleeve 42.

A longitudinal adjusting bar 4'! for the rotary guard 35 is provided, and extends adjacent to the clamping nut 32 and turning lug l 6 of the adapter 13, as shown. The forward end of the adjusting bar 4'! carries a short integral transverse extension 48 which is inwardly directed and rigidly secured by welding or the like to the head 42. The adjusting bar 41 is spaced somewhat from the sides of the nut 32 and turning lug I5, as shown, for the convenience of the operator. The adjusting bar 4! further comprises an inwardly offset straight longitudinal trailing xtension 49, which bears lightly against the periphery of the rubber tube l3 for steadying the adjusting .bar 47 as the same is turned circumferentially about the tube l3. By means of the adjusting bar 41, the oper ator of the implement may readily turn the guard 35 circumferentially about the burr 29 to any selected adjusted position, and the adjustment of the guard 35 may be accomplished with one finger of the hand which holds the implement. Whenthe guard 35 has been shifted to the select ed circumferentially adjusted position, the trailing extension E9 is clamped by the fingers against the rubber tube 13, and this serves to hold the guard 35 stationary in the selected adjusted position. I have found it convenient to arrange the transverse attaching extension as of the bar 3'! at an angle to the side opening 38 and flat face 4! of th guard, as best shown in Figure 4. However, the guard m-ay be adjusted satisfactorily with the extension 48 arranged in any circumferential position with respect to the side opening 38 of the head 35, and the position of the extension 43 in Figure 4 is merely a preferred position.

During the operation of the implement for grinding the small tusks of a chinchilla, therubber tubing section l3 serves as a handle, and this handle and the flexible sheathing I3 do not rotate. The rotary drive shaft 21 rotates the chuck. 2B and intermediate adapter !3' as a unit, along with the clamping unt 32, spindle 30 and burr 29. A rotary holding unit is provided, including the adapter 13 and all elements mounted thereon. The holding unit includes the skirt portion l4, chuck 20 mounted within the adapter and nut 32 to operate the chuck for clamping the spindle 39. The skirt l t enables the rotary holding unit to be mounted upon and within the sleeve H included in the handpiece. The guard 35 is non-rotatable, except for adjustment, and is held stationary by clamping the trailing extension 49 against the handle 13, as previously stated. Ihe clamping nut 32 and adapter l3 are caused to rotate with the drive shaft and chuck 29, due to the wedging engagement of the shoulders l9 and 34 with the tapered parts 25 and 22 of the chuck head 2i. Th cylindrical skirt portion 14 of the adapter 13 forms a lon bearing within the non-rotatable rigid sleeve H for the entire rotating unit of the implement.

The forward end of the implement is introduced into the mouth of the chinchilla, which is held open by suitable means, and the rotary guard 35 is adjusted so that'the tusk to be ground may enter the side opening 28 and engage the side of the rotary burr 29. The head or body portion 33 of the guard now protects the mouth of the animal from contact with the burr 29, and the guard is held in the selected adjusted position by clamping the extension 43 against the handle l3 with the fingers. The guard 35 may be adjusted freely for a full 360 degrees about the burr 29 by merely engaging the bar ll with a finger of the hand holding the implement.

I wish to emphasize that the forward portion of the implement including the sleeve 42 and guard head 36 are extremely narrow or slender, so that the implement may be introduced into the mouth of a chinchilla, which is very small. The adjusting bar 47, clamping nut 32 and other relatively larger parts of the implement are all spaced well rearwardly of the portion of the implement which actually enters the mouth of the chinchilla. The only portion of the implement which will enter the mouth is the head 36, and perhaps a small length of the sleeve 42. The extreme smallness and slenderness of these parts may readily be seen in Figure 10 which is intended to illustrate substantially the actual size of the implement.

It is to be understood that the form of the invention herewith shown and described is to be taken as a preferred example of the same, and that various changes in the shape, size and arrangement of parts may be resorted to, without departing from the spirit of the invention or the scope of the subjoined claims.

Having thus described my invention, what I claim is:

1. A grinding implement comp-rising a hand piece, a rotary holding unit journalled upon the hand piece, a flexible drive shaft connecting with the holding unit to turn it, a slender spindle held within the holding unit for rotation therewith and extending forwardly of the holding unit, a grinding burr secured to the slender spindle, a sleeve surrounding the slender spindle forwardly of the rotary holding unit and serving as a bearing for the spindle and being slender, a guard carried by the sleeve and partially surrounding the grinding burr and having a side opening for exposing a side of the burr, and an adjusting handle secured to the sleeve rearwardly of said guard and having a part extending adjacent to said hand piece and adapted to be held by the fingers for securing the guard in the selected circumferentially adjusted position relative to the burr.

2. A grinding implement comprising a narrow hand piece, a rotary holding unit journalled upon the hand piece, a flexible drive shaft connected with the holding unit to turn it, a slender spindle held by the holding unit for rotation therewith and extending forwardly of the holding unit, a small grinding burr carried by the forward end of the spindle, a slender sleeve surrounding the spindle forwardly of the holding unit and serving as a bearing for the spindle and having its inner end engaging the forward end of the rotary holding unit, a guard secured to the forward end of the sleeve and surrounding the grinding burr and having an opening in its side for exposing a portion of the burr, and an adjusting handle secured to the sleeve near its end adjacent to said holding unit and extending longitudinally of the hand piece and spaced laterally for a portion of its length from the hand piece, a rear part of the adjusting handle being arranged close to the hand piece and. adapted to be clamped thereagainst by the hand holding the hand piece, the adjusting handle, sleeve and guard being adjustable circumferentially of the hand piece and burr for a full 360- degrees.

3. A grinding implement comprising a tube adapted to serve as a handle, a rotary holding unit including a sleeve portion journalled within the tube, a flexible drive shaft leading into the tube and connected with the holding unit to turn the same, a slender spindle gripped by the holding unit and extending longitudinally forwardly of the holding unit, a grinding burr carried by the forward end of the spindle, a guard partially surrounding the grinding burr and having a side opening exposing a side of the burr, a slender sleeve carrying the guard and rotatably receiving the spindle rearwardly of the guard and having a rear end engaging the forward end of the rotary holding unit, a longitudinally extending guard adjusting handle connected with said sleeve near the rear end of the same and spaced a substantial distance rearwardly of the guard, the handle being spaced somewhat laterally of the rotary holding unit and tube serving as a handle and substantially parallel therewith, and a trailing extension car ried by the handle and slidably contacting the periphery of the tube serving as a handle and adapted to be clamped thereagainst by the hand holding the implement for positioning the guard in the selected adjusted position.

4. A grinding implement comprising a tube adapted to senve as a handle, an adapter element including a sleeve portion journalled within the tube and having a bore, a gripping chuck mounted within the bore of the adapter element and having jaws projecting forwardly thereof, a flexible drive cable leading into the tube and sleeve portion of said adapter element and secured to said chuck, a clamping member mounted bodily upon said adapter element and being adjustable and engaging the jaws of the chuck forwardly of the adapter element, a slender elongated spindle held by the jaws of the chuck and projecting a substantial distance forwardly of the chuck and clamping member, a grinding burr secured to the forward end of the spindle, the spindle, clamping member, chuck and adapter element forming a rotary unit, a slender sleeve surrounding the spindle forwardly of the clamping member and chuck and having a rear end engaging the clamping member, a guard secured to the forward end of the sleeve and at least partially surrounding the grinding burr, and a longitudinal guard adjusting handle secured to the sleeve near its rear end and extending adjacent to the tube serving as a handle to be held thereagainst when the guard is in a selected adjusted position.

FREDERICK C. FEI-BMAN.

References Cited in the file of this patent UNITED STATES PATENTS Hicks Oct. 21, 1947 

